Method for producing light metal pistons running in cylinders of harder material



CH K792 583- ME'TAL PIST HARDER MATER AT Bw NMO E s RWR 2. M

METHOD RUNNIN ii ab mwm.

ONS, IAL

FFE FOR PRODU G IN CYLINDE Filed A Patented Feb. 17, 1931 UNITED STATESPATENT OFFICE METHOD FOR PRODUCING LIGHT METAL PISTONS RUNNING INCYLINDERS OF HARDER MATERIAL Application filed August 12, 1927. SerialNo. 212,578.

' terial whether the separate particles are of greater or smaller sizeand the intervals in light metal are of like or different size. Theactual running surfaces of the piston then form the harder superficialparticles embedded in the light metal, whereby the surface in contactwith the cylinder and consequently the friction, are reduced. Theseintermediate layers of light meta-l between the hard particles are alsosuitable for taking up lubricants, so that the easy sliding of thepiston in the cylinder is obtainable.

Such hard particles distributed in the light metal may, for instance, beproduced by adding in the alloy a greater or smaller quantity ofsubstances which only dissolve partly or not at all in the light metaland again crystallize or separate out. It is also possible to alloy withthe light metal substances which remain distributed in the liquid masswhen poured in or introduced, or which are only partly dissolved, where,for instance, the quantity added exceeds the limit of dissolution andconsequently produces separation. It has now been found that suchpistons can only be used in practice if they are cast in such way thatthe axis of the piston, when cast, stands vertical. A mould as used forthe above purpose is shown by way of example in Fig. 1 is a section online AB of Fig. 2.

Fig. 2 is a section on line C.D of Fig. 1.

Fig. 3 is a section on line E-F of Fig. 2.

Fig. 4; is a section on line G-H of Fig. 3.

Fig. 5 is a section on line I-K of Fig. 3.

The casting mould a consists of metal, for instance iron, and hasflanges b supporting the outer metallic cores 0. A central core (1presses the two outer cores 0 against the .moulda and two other cores fare about in the centre of the mould. The casting holes 9 are shown inFig. 3 and the various cross sections in Fig. 4. Fig.3 shows that thelateral limit lines are straight and the cross sections show that thecasting hole is circular at the top and longitudinally rectangularbelow. For the practical application of the. method aluminium andsilicon, for instance, are suitable. It has been found that the bestcast is obtained by using perfectly pure metals. Alloys suitable inpractice must have an addition of silicon exceeding 18%. For example, anaddition of about 20-25% of silicon is very suitable. It is possiblehowever to go up to 35% and event higher. For aluminium, in particular,the best application of the process is obtained if new aluminium only isused and not aluminium that has been remelted. To the aluminium is addedmetals or metalloids up to 5% of the total cast, in order to improve thecertain,

other properties of the casting.

The metals or metalloids thus added are harder than aluminium and aresuch as are well known, a partial list including silver, copper, boron,zircon, beryllium, magnesium, titanium, vanadium, manganese, molybdenumand chrome- I claim 1. The method of casting articles such as pistons oflight metal weight for engines, consisting in melting a light metal,embodying into said molten metal silicon constituting in quantityapproximately 18% of the ultimate metal mixture, adding to aforesaidmixture particles of hard metals in amount approximately 5% of theultimate mixture, pouring the molten mass into a vertical mold, andchilling the mass, whereby the hard metal particles are distributed overthe surface of the casting.

2. The method of casting articles such as pistons of light weight metalsfor engines, said method consisting in melting aluminium, embodying tosaid molten aluminium silicon in'an amount constituting approximately18% of the metal mixture, adding to aforesaid mass into a vertical mo d,an

mixture 2. quantity of particles of hard metals in amount approximately5% of the ultimate metal mixture, ourin the molten chilling the masswhereby the hard metal particles are distributed over the surface of thecasting.

In testimony whereof I afilx m signature.

FRITZ FEI-IRE BACH.

